[Chandler-dev] Use of OPTIONS instead of PROPFIND

[Morgen Sagen]

I'm trying to dig up my notes about the choice of PROPFIND so I can  
give a full response to this, but keep in mind this is not for a  
sync, only a subscribe.  A sync is simply a GET followed by a POST.

On May 16, 2007, at 2:23 PM, Jared Rhine wrote:

> What follows is an inquiry about the advisability and effort of  
> using HTTP "OPTIONS" instead of "PROPFIND" for Chandler to  
> determine if a given URL is a DAV URL.  The inquiry is primarily  
> directed to Morgen.
>
> I've spent a couple days looking at the server-side of a real-world  
> Morse Code driven service looks like.  The standard pattern for a  
> synchronization is a 4-transaction HTTP set:
>
> 71.202.115.113 - - [16/May/2007:13:45:17 -0700] "PROPFIND /pim/ 
> collection/723886a6-705d-11db-8ee8-99b22f7fce88?ticket=1zaf4xxac0  
> HTTP/1.1" 501 1238 "-" "Chandler/0.7.dev-r14332 (Linux; U; i386;  
> en_US)"
>
> 71.202.115.113 - - [16/May/2007:13:45:17 -0700] "HEAD /pim/ 
> collection/723886a6-705d-11db-8ee8-99b22f7fce88?ticket=1zaf4xxac0  
> HTTP/1.1" 200 - "-" "Chandler/0.7.dev-r14332 (Linux; U; i386; en_US)"
>
> 71.202.115.113 - - [16/May/2007:13:45:17 -0700] "GET /pim/ 
> collection/723886a6-705d-11db-8ee8-99b22f7fce88?ticket=1zaf4xxac0  
> HTTP/1.1" 200 5533 "-" "Chandler/0.7.dev-r14332 (Linux; U; i386;  
> en_US)"
>
> 71.202.115.113 - - [16/May/2007:13:45:17 -0700] "GET /mc/collection/ 
> 723886a6-705d-11db-8ee8-99b22f7fce88 HTTP/1.1" 200 1243606 "-"  
> "Chandler/0.7.dev-r14332 (Linux; U; i386; en_US)"
>
> So, it's a PROPFIND + HEAD + GET /pim + GET /mc.
>
> The initial PROPFIND operation helps Chandler determine if it's  
> working with a DAV-based URL.
>
> Essentially every Chandler-driven PROPFIND against the server will  
> fail.  This is per the design.
>
> However, it tweaks a little muscle in my sysadmin head: looking for  
> 5xx errors in an access log is one of the primary ways to tell if  
> something is breaking on the server.  You better pay attention if  
> that metric suddenly spikes.
>
> So I've a mild aversion to a regular, everyday operation generating  
> what looks like an exception condition.
>
> All Chandler is trying to do is figure out if the URL is a DAV URL.  
> There's already a standard WebDAV mechanism to determine this; it's  
> the HTTP OPTIONS method.
>
> I hesitate to even ask the question as what we have now works, and  
> it'd be a Morgen task, and Morgen is quite the busy camper these  
> days.  But the question is out there now, and I'm guessing I'll get  
> a pretty reasonable answer that a good balance of these concerns.
>
> Thoughts?
>
> -- Jared
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